EARTH IN SATURN'S SHADOW

This beautiful image of Saturn and its rings looks more like an artist’s creation than a real image, but in fact, the image is a composite (layered image) made from 165 images taken by the wide-angle camera on the Cassini spacecraft over nearly three hours on September 15, 2006. Scientists created the color in the image by digitally compositing ultraviolet, infrared, and clear-filter images and then adjusting the final image to resemble natural color. (A clear filter is one that allows in all the wavelengths of light the sensor is capable of detecting.) The bottom image is a closeup view of the upper left quadrant of the rings, through which Earth is visible in the far, far distance.

On this day, Saturn interceded between the Sun and Cassini, shielding Cassini from the Sun’s glare. As the spacecraft lingered in Saturn’s shadow, it viewed the planet’s rings as never before, revealing previously unknown faint rings and even glimpsing its home world. Seen from more than a billion kilometers (almost a billion miles) away, through the ice and dust particles of Saturn’s rings, Earth appears as a tiny, bright dot to the left and slightly behind Saturn.

Although it might appear that Earth is located within Saturn’s outermost rings, that positioning is just an illusion created by the enormous distance between Cassini and Earth. When Cassini took this image, the spacecraft was looking back at Saturn from a distance of about 2.2.million kilometers (about 1.3 million miles). The Sun was millions of additional miles beyond, hidden behind Saturn. On September 15, Earth’s orbit had brought our home planet to a location slightly behind and to the left of the Sun from Cassini’s perspective.

Here is the website to get more enthralled!
http://ciclops.org/view.php?id=2230&js=1

The STEREO Ahead spacecraft kept a close eye on two active regions on Feb. 12, 2010. The one on the left popped off a small flare. The still shows the bright flash of the flare in UV light at 195 Angstroms. The active region near the center shows a lot of magnetic struggles within it, and it bursts out a small coronal mass ejection (CME) after the arch of particles is seen rising up. Flares are intense explosions on the Sun that blast out radiation into space. CMEs are larger and longer lasting solar storms that carry a larger cloud of particles and magnetic field into space. Both can create what we call "space weather" effects such as power disruptions, satellite problems, and aurora if aimed at Earth.

IMAGE FUSION

PROBLEM :

HOW DO WE GO ABOUT FUSING A MICROWAVE IMAGE AND OPTICAL IMAGE OF A SAME AREA ?

The conventional style of Georeferencing always exists. But what if we are not microwave specialists and could not identify features just by seeing?
If we go for a path and row we can find only a scene and not a specific point which we would require to georeference an image and thus fuse them. Further its a critical situation if we use a fusing of an Interfereogram.

A new dimension to GPS through SONAR

GPS does not work underwater-the radio signals on which it depends cannot pass through water. So submariners have yet to benefit from the revolution in navigation that it allows.

Now engineers working for the US Office of Naval Research think they have found a simple way to let submarines and divers get an accurate GPS fix.

A base station is tethered to the sea bed at known depth and known GPS location. A submersible anywhere in the area sends out a sonar request pulse to which the base station replies with a signal which gives its GPS position and depth as well as the bearing angle from which the submersible?s request arrived.

The submersible then uses its own depth, which is easily measured, plus the round trip pulse time and the bearing angle sent by the base, to calculate its own position. Simple.

Reference :
http://www.divespots.com/pdf/DiveSpots_article_uwgps.pdf